Hello, Soliloquy most of the time recommends a solid state amp. I think they prefer the higher damping factor of a solid state amp over a tube amp. However, look on the Soliloquy web-site in the Reviews Section. The reviewers loved the speakers with tube amps. Some of the reviewers used small 20-30 watt amps with great success. If you have a tube amp with great low end control, I see no reason not to use it with the 6.3s. Read all the reviews on the 5.3, 6.2, 6.3, and the 6.5's. Soliloquy comments on all the reviews. Read these comments for Soliloquy's advice. As a rule, all Soliloquy speakers are very easy to drive with over 90-92 db sensitivity at 8 ohms impedance. I have a pair of the 6.5s and I use a solid state amp but feel that I could/might use a tube amp with them in the future. The owner of Soliloquy is very helpful. Give him a call for advice. I did. Jim